1. Laboratory of Cardiovascular Medicine, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
2. Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Kita-15 Nishi-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan
3. Division of Diabetes, Metabolism, and Endocrinology, Department of Medicine, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan
4. Department of Internal Medicine, Ushioda General Hospital/Clinic, Yokohama, Japan